The present invention pertains generally to high-temperature resins and in particular to cyano-addition resins from oxyarylbisorthodinitriles.
It is known that certain bisorthodinitriles polymerize to form strong, high-temperature thermosetting resins. Examples of bisorthodinitriles suitable for producing these resins are disclosed in U.S. Pat. Nos. 4,056,560; 4,057,569; 4,116,945; and 4,136,107 by James R. Griffith amd Jacque G. O'Rear.
The structure of these resins is not completely known. For the following reasons, the principal mechanism of formation is theorized to be phthalocyanine nucleation. As the bisorthodinitriles polymerize, the color becomes progressively darker green in the manner similar to phthalocyanines. The polymerization is difficult to initiate and promote which indicates the formation of a large and complex nucleus such as the phthalocyanine nucleus by a charge end group such as the phthalonitrile group.
The resins have properties that make them exceptionally suitable for structural resins. They have a structural strength comparable to that of epoxy and polyimide resins and have many advantages over these resins. They have a maximum temperature stability in an oxygen-containing atmosphere of about 230.degree. C. which represents a significant improvement over epoxy resins and their water resistance, as measured by the water-soak method, is better than that for epoxy resins. These resins have many advantages over polyimides due to the absence of solvents, being less hydroscopic, and not being thermoplastic with a low glass transition temperature. Thus, polyphthalocyanine resins promise to be an important new class of structural resins.
Much interest has been shown in improving the adhesive strength of polyphthalocyanine resins in order to obtain an adhesive with the exceptional properties of polyphthalocyanines and to improve the toughness of polyphthalocyanine composites.